TRS-80 Model III rebuild project - "Retropie BattleStation"

iainjh

New member
AmiBayer
Blogger
Joined
Mar 2, 2010
Posts
2,796
Country
England-Shire, UK
Region
High Wycombe,UK
I have been given a smashed up TRS-80 Model III shell. And I have evil plans to resurrect it ;) Here I'll try to post a diary as I go along.

The story is, it was shipped from USA as a working machine but unfortunately arrived with the monitor and motherboard smashed to smithereens, and with most of the internal mount points sheared off. It's been sat at TheCorfiot's for a few years and presented with a challenge, I'm going to try to salvage the case into something usable!

Initial concept is to transplant an LCD and get the keyboard working with a raspberry PI model 3 and emulate most of the home computers of note in one proper terminal-style Retro BattleStation. Emulation is one thing, but presentation and aesthetics are important too.. can I get that right? So the shortlist must include TRS-80 Model 1/3 as well as 4, plus the essentials of Atari 800, C64, Oric, Pet, C16 (commodore's via Vice under Retropie or Combian), of course Amiga (Amiberry)...certainly coco's and Dragon32, SCUMM, Speccy, 6128. I really want to get the BBC emulator compiled and working under retropie/ Emulation Station, set up in the menu's etc.

How hard can it be? It will take some engineering to fit the screen nicely and will need to surely cut away some moulding from where the CRT was...how to mount the LCD? How to make it flush, car filler might be a plan. How well will the screen be presented, and will the look be credible?

OK lets do this.


Step 1: initial plans
Initial thought was transplant an LCD into it and either ask Dave at Tynemouth software to build a custom usb encoder to re-use the original keyboard (which he can surely do, clever chap - see his blog at tynemouthsoftware, he has form), or to create a driver and read the keyboard in over the GPIO pins. The wiring seems straightforward as its an 8x8 matrix but the software and config is fiddly. I dont know how well the keyboard works. Will it work in Retropie? not sure. But with Tynemouth's expertise, yes.

I also find the keyswitches in the TRS are very very similar to Cherry MX. I could undersolder them all if I need to, but nagging thought it the TRS has a decent amount of keys missing, no F keys, that might harm a credible emulation station. hmm..

Or, I could kludge/ engineer a modern USB keyboard in and get the look right with new /retro keycaps...

Onto the LCD - the screen was 12" and over the last months I've found a few 800 x 600 res LCD panels and driver boards. After a few weeks of debating if 800 res was too low to be of any decent quality.. aha! Now I have found a 12.1" LCD, in a metal frame on alibaba. 4:3 ratio, seems almost the exact size, £60 quid. 1 x ordered.

Step 2, measure properly, clean the case
..and confirm exactly how the hell to do this.


Bathe her and bring her to me. Don't tell the wife what I used the downstairs shower for.
IMG_0714.jpg

Direct-to-floor cleaner is usually best, today Flash got the job. Filthy. Hands now sore:(
IMG_0715.jpg


I've now noticed the black moulding can be removed. It's all smashed on the inside anyway. Maybe instead of machining/ filing this flat to suit the screen I can do a better job removing it altogether.. OK, measure it up..
IMG_0716.jpg

The case outer is in pretty good nick! and re the screen opening, she's wider at the top than at the bottom. Ooo. 275mm x 215mm.
IMG_0717.jpg

Forgive the pics being askew. I'll post some pics in the next weeks as I fix this up and work out a couple kinks along the way.

part 2 coming soon
 
Scrubbed up nicely - looking forward to see how it all comes together!
 
The screen arrived! It's very good, the backlight is nice and bright - thats a good thing as i have also just ordered some 5% smoked grey perspex cut to 275mm x 215mm (ebay, £10). I will work out how to mount that later but likely to be flush to the front face of the case with the screen flat behind (where the weight will be taken on the remaining screw holes).

the screen came with a curious metal frame, and a vesa mount that I may need.

BUT

now I've decided not to trim all the curvature off the screen surround.. the case hole looks to be able to take a 13" 4:3 and the 12.1" is maybe too small. OK, so old computers usually had small screens/ big surrounds (it would just mean a big black border, could look good.. but I find myself now looking for a 13" LCD... that's probably a waste of cash and likely hard to find a non-widescreen panel that size.

But if I put the surround back in (to fill the border in a 80's way) I loose all the newly released mount points and space for the supporting frame I have to make..

hmm..

quick search... ok this looks the right size. lucky boy.

https://www.alibaba.com/product-det...galleryofferlist.normalList.83.64264223phBPhQ

They're may be some out there. Hope I can just get the panel and driver board, I'll need send some emails..

I've also ordered the speakers, I have some of these already and they are so cheap how to say no. USB powered.

Good news I got the mount out ok. Screws were under the TRS badge
IMG_0728.jpg


Laid up, alignment. A wood frame screwed to interior mount points with cross brace holding the screen to that, gives room for adjustment. I think. But the gaps are bigger than I expected. rats.
IMG_0733.jpg
 
Decided to stick with a 12.1" screen. its got about 1cm border, thats all, have to think up a scheme to mask it off with black from the inside, and do it well so it looks "original".

And the screen plastics have arrived. With this, the plan is to sand the corners rounded to fit the profile of the shell, fit flush. I got the offcut plastics as well so if I'm a mm off with my measurements i can cut another slightly larger.. this has to be good. Then, (THEN) I need work out how to fix the screen plastics to the shell. Present plan A, is as its such a snug fit to mount the LCD panel, and then mount the plastics to the panel. Something high capital cost... or duck tape. it will be needed to keep dust out from behind anyway, and it wont be seen, and will be removable. I think that will do.

screen perspex; initial checking of size, before fitting
IMG_0749.JPG

Panel, naked
IMG_0741 (1).jpg

panel, even more naked
IMG_0742.jpg
 
Got an email back from an alibaba vendor. There is a 13.3” sony 4:3 panel - however 13.3 visbible dispkay won’t fit andbim not ruining the case to jam it in. So 12.1” panel is a-ok

bought some 5mm x 34mm wood strip to start preparing the screen mounts. And, ordered a key switch , an illuminated reset switch and some illuminated blinkenlights. I also threw £2.99 at a multi-7segment panel in case I can make that look good. These may go in the bottom ‘hole’ when it’s filled in. Will see....
 
Simplified plan re: mounting the perspex and LCD panel to the shell. I listed the requirements and decided against wood and brackets at this point. I might need the bracket space to mount the LCD driver board and wood may be too bulky. I got the offcuts along with the main screen piece, so i'm going to use those, they are very strong for their size.

Plan B is now to glue small offcuts to the perspex, and those to the shell, then I'm going to use.. duck tape to mount the LCD to the perspex AND the shell to spread the load, its not heavy and the panel will be removable.

I masked off the edge of the perspex to match the bezel, and painted the border solid black from the inside.

No pics, just post it sketches working this nonsense out :)

measured in mm not inches, obv's :)
IMG_0764.jpg

Engineering drawings. And if it isn't strong enough, add more tape.
IMG_0763.jpg
 
Update:

araldited the perspex in, I bodged up the chamfered corners unfortunately so I may need re order the plastics. Maybe..

For a mockup, I attached the LCD panel with 25% of the duck tape I thought i'd need.

the black border edging looks fantastic, perfectly black and sharp edged.

the screen though has a rabidly bright backlight so I may put 2 layers of pespex together to darken it more. I have the offcut ready to test that.

I also like it now in silver, i think that will be fine.

Do you like the keyboard? a cherry MX propped up with a cheapo $9 set of keycaps. off white and orange 70's. i think I'm going to use this not the real keyboard!


flush
IMG_0781.jpg

Sam Coupe? TRS also :)
IMG_0782.JPG

Flip & Flop, the traditional test
IMG_0784.JPG
 
Thx Bas!

I havent yet tried the double layer of acrylic to tone down the excessive backlight. There's no way of adjusting it on the LCD or the backlight module its far too bright.. I have ordered a darker grey bit of acrylic (perspex) to hide that as I dont think 2 layers will be good enough.

I've next to work out how to mount the keyboard! I need drop the keyboard height so the keycaps arent so proud through the upper shell. They presently sit a bit high. Mounting will take some cutting of the lower case, and adding something to give a future way of adjustment. The keyboard base fits to the lower base and sits flush in the upper, and to ensure there's no gaps around the edges I have a cunning plan involving 20mm x 20mm wood and some textured 1.5mm thick plastic sheet.haha

Hopefully this weekend i'll mock this up and will post some pics.
 
Last edited:
Is there no POT on the controller board to adjust the Brightness voltage. The ones we used on the SX64 upgrade had one :)
 
did they?

I didnt see anything.. I might have only looked at the backlight board. I'll have a closer look tonight as it is a touch bright!

ta:)
 
I think my doubts over the quality of the lcd panel and driver board are justified, its crp. possibly the driver board.

cheapest way to fix this, I gutted an "eyoyo" brand 12.1" LCD, down to the panel and driver boards, and all is far better. Better blacks, contrast, the backlight is far better.

thats now in. took some ropey old adjustments to my black borders as the screen frame was a bit bigger..that is a bit rubbish tbh but hopefully no one will notice.

its fixed in to the acrylic with existing araldited in offcuts, plus lots 3M fabric tape, hopefully it'll stay in!

next up: I have some black textured 1.5"" plastic sheets, like 5.25" floppy disk plastic.. this surrounds the keyboard and fills the top drive bay. To mount the keyboard I have to make a frame around edges with 10mm x 10mm wood, and under, with inverted screws to adjust the height front and back. Lots of fiddling...

Ive received some rgb led strips and 7 segment display strips, these will be driven by python from the pi. 70's Blinkenlights.

The top drive bay, blanked off, will be the blinkenlights position, the sd card, plus the reset switch and the lcd brightness buttons etc... the lower is a plastic food storage box from sainsbury's, I'll spray it's outside black and that is where the ps3 controller can go when out of use. Storage.

USB powered speakers are in on the lower tray... got to get a mains extension lead, then wire up the pi power switch to the TRS original on/off switch...


pics:

LCD screen alignment bay, ie wedged upside down in a chair:)
IMG_0913.jpg


Fabric tape testing.. is it strong enough..
IMG_0915.jpg
 
Last edited:
Mock-up of the lower panel. I have a keyswitch to add plus the lcd control buttons.

Leds and segment displays all driven over serial from the pi, python. He hopes.

Must wire and test them all before cutting as this’ll be tough! Will take a while before I get to cutting..

checking it fits, kindof
IMG_0919.jpg


Mockup...How the heck am I going to get this cut straight?. thats a key.
Screenshot 2018-09-15 at 23.44.34.jpg
 
Last edited:
todays fun

Ive not done anything yet with the blanking panel or the wiring.

But the usb keyboard has some ugly and modern graphics on, plus there'd be a gap around the edges so I got some nice carbon printed plastic, from a notebook binder to stick to the keyboard face. 2 pieces of A4 to cut and merge to give it a nice effect.

pic: making a template. I have to cut this out, stick it down and match it up. then I'll test it, then cut the final plastic, glue it on and test in situ.

Next will be to build the keyboard supports and get aligning.

wip:... papercraft

IMG_0968.jpg
 
Update:

Still not got round to the display panel thing.

For the keyboard surround, where before it had gaps around the edges and the awful 2018 vintage "wicked-keyboard-graphics" I found a display book bnider in WHSmiths that's cover had a nice carbon fibre effect. I have now cut that to shape and fitted it. I didnt bother with the caps--lock LED holes as would look rubbish however I did them. I rushed the left side a bit so it's not as neat, and made up of offcuts, I may redo that sometime. I did aim to get the joins out of sight under keys so there's no real obvious cut lines.

Pics:

layout, scissors, wire snips
IMG_1012.JPG

Full range of weapons to hand
IMG_1010.JPG


Dry run, right side
IMG_1013.JPG

In situ test. Dabs of UHU to fix in place. Next, get the keyboard height correct between the TRS' Lower and Upper case parts so it's flush and to then trim, err, the trim, around the bracket holes and screws etc, to fit spot on.
IMG_1015.jpg
 
i've added a neat little box behind the top drive bay. Its suitable sized for a controller or spare micro sd card or stick.

Was going to make it deeper but then I wouldnt be able to reach in to retrieve whatever went in there.

Sprayed the inside with car bumper grey flexible paint, stuck it in with the almost- inevitable... fabric tape. I hope the half-life of the tape sticky is a long time!

2 pics to add:

Lining up: also the bottom flat panel, with the red reset switch and the power key switch. need to take these out and get the 7-segment LED's cut in. After ive got the python working and the wiring done!
IMG_1033.JPG

BT controller, testing testing: hasnt fallen out yet
IMG_1032.JPG


Good news is I'm close to getting the wiring underway.
 
Last edited:
ive not forgotten this. Just ran out of ideas how to make the lower panel as good as it needs to be.

Plan B
Much less cutting.
I'll use some remainder smoked perspex and mount the 7-segment led's flush to the rear so invisible when off.
Clear self adhesive laser-printable a4 sheet.
i'll layout a black background with CLEAR retro font labels next to the lights and 7-segments...not sure what but nonsense like "writes /store" or whatever, proper 70's retro . stick it to the rear, should make a better job. Will look fab lit by leds from behind when on.

right, get to it ;)
 
blimey, 16 months later..

OK i didnt forget, but I fretted to long about how to print the graphics and gave up after 5 or so attempts. Laser printing the art onto self adhesive transparency went ok for a while but once applied looked poor, so that was abandoned in favour of a custom screen on the LCD screen. The lower panel still has a couple led strips and a 7 segment display driven by some python script. that works well and nicely flashy.

So its all up, working, the lid is on and it works really well.

The biggest issues remaining are: old cold cathode backlit screens arent bright enough and 1024 x 768 res screens arent really high enough res. Ok for old 320 x 240 games but UI's look a bit dim, sometimes ragged.

panelook.com is a fantastic resource for finding panels, theres some 1600 x 1200 4:3 screens but too costly for what is just a plaything. Also finding the exact right LVDS cable, controller and firmware takes too much time from games themselves!

I need to finalise the mounting of the screen as in the warm weather its slipped 2mm.

The stock pi PSI needs to be upgraded as there's a volt drop through my key switch.

other things:

BBC, electron are a joy, as are commodores on a big beast battle station of a machine.

I've made a couple standalone PI micro-sd cards - atari st, falcon, amiga, zx spectrum next, baremetal CBM, these are cool to slot in and boot as if were the real thing. But retropie is by far the easiest.


pics coming
 
Pics:

the python scripts arent running. I'll get to those. But the lid is ON! Screwed on!

I've now swapped off a couple keycaps (page up/down etc), as the keyboard is backlit these now correspond to start/select in Emulation Station. I might add some transparent decals to the front face of those as i can do those well.


Led and 7-segments, and lego:
IMG_4716.jpg


Obligatory in-action pics:

Mac:
IMG_5396 2.jpg


Emulation station:
IMG_5389.jpg


ST (useful!) or falcon (mostly pointless, oooh controversial):
IMG_5382.jpg


Half-Life emulation!
IMG_4938.jpg


Flip & Flop! Atari 800
IMG_4937.jpg

Nekkid filth pics. I should have taken some pics of the lego araldited to the back of the lower acylic panel., holding the led strips and 7-segment square.

These likely look scruffy. Wires to the LCD driver panel at the top, and from the PI to the 2 x UB ports cut into the rear panel, and of course the Micro SD extender and USB to the front. I leave a wireless mouse sender in the rear panel leaving one free.

IMG_4928.jpg


full frontal
IMG_4927 2.jpg


lots of wires between the ic2 and led strips and the GPIO. and for power and pi shutdown pins 5,6
IMG_4923 2.jpg



right, i'm done, time to use it! :)
 

Attachments

  • IMG_4712.jpg
    IMG_4712.jpg
    196.6 KB · Views: 3
Last edited:
Found a couple more pics, cutting and gluing the lower panel:


markup
IMG_4721.jpg


lego time - lining up, dabs of hot glue will be needed to lock the leds to the lego.
IMG_4716.jpg

cutting
IMG_4768.jpg

araldited and dabs of hot glue
IMG_4717.jpg

wiring and assembly
IMG_4775.jpg

fixings from front
IMG_4774.jpg

cutting self adhesive decals
IMG_4778.jpg


I took the decals off, they looked overwrought, and dark - cant print white.
IMG_4780.jpg


Testing the screen: With the classic film Fist of jesus :)
IMG_4797.jpg

boot screen for the panel - that will do:
IMG_4798.jpg
 
Last edited:
Back
Top Bottom