A more compact, BBC Master Compact

  • Thread starter Thread starter iainjh
  • Start date Start date
  • Replies Replies 34
  • Views Views 15744

iainjh

New member
AmiBayer
Joined
Mar 2, 2010
Posts
2,796
Country
England-Shire, UK
Region
High Wycombe,UK
Hi Amibayers

A BIG Post for a compact... and lots of Pr0n :)
.

Here's an attempt at a photo diary modding a BBC Master Compact. I’d sent thecofiot a couple of in progress pics and he suggested I photo-booth it! So here it is :)


I love the BBC Micro and reckon they are amongst the very nicest of any Brit 80’s micro. Top 3 for definite. So there!

Why a Compact and not a Model B or Master? I already have a Model B, and want one for the kids. However there isn’t enough space for another computer in the family room... yes, this really is for the kids to play with and learn a little BASIC. But there’s zero room for a full-size BBC and definitely no room for another TV or monitor.

Then on amibay I read about the 8220 and 8220 RGB>VGA converters. Hmm.... a ‘light came on’ when I saw a Master compact for sale, but just the keyboard! Could it work without the base? The Compact was a 2-part computer, a keyboard with the CPU and much of the Master’s innards, and a separate PSU/disk drive base for under a monitor. A little research confirmed the master runs off 5v, and there’s little in the base unit beyond a PSU, floppy drive and an awful lot of air! The compact is mostly a BBC Master without the Tube and User ports. So this is how the plan formed..


  • Clean it up, a quick dose of Retrobrite if needed
  • Get a 5V 2 or 3a PSU
  • Add the 8220 RGB>vga converter internally if space under the keyboard
  • Add a power socket and switchfor the Compact and the VGA card
  • Add a VGA 15-pin socket out, ideally cut into the back panel
  • Add a speaker line out (with a volume control) for the same ‘family pc’ monitor (as the beeb audio is a bit harsh)
  • Finally use the ‘turbo mmc interface’ I bought last year
My initial thoughts with the 8220 were to just run a cable through another spare ‘hole’ in the case, but thecorfiot reckoned that was a bit ‘poor’ so out with the tape measure and pencil and I dremel’led in a space for mounting a VGA socket as well as a new slot to fit the MMC card.

Cheers Bas you were right, it looks much better now, what was I thinking Lol


In test: the compact arrived, needed a clean, but spotless inside and working well
">


Cleaned up



Adding the VGA and MMC boards:
Really luckily, the compact has a couple of spare pre-cut holes in various places around the case, with blanking plates screwed over them.. one looked large enough to almost fit a power switch (looking at all these, surely planned by Acorn, the hole is in such a perfect position) and with some jiggling I found a good, but tight spot for the VGA converter card in the case.

Lots of measuring later, (blobs of blu tac to check free space remaining in the case), and with a few input sockets receiving a severe haircut, the VGA board fitted with 1-3 mm to spare. I soldered the RGB inputs to the underside of the Compacts’ RGB out.

Haircut:
">

And, a near perfect picture!

IMG_4600Medium.jpg


In progress set of ROMs:
IMG_4631Medium.jpg



Unused holes, perhaps acorn had intended to use them for other things? (plus my pencil marks, rear panel for the VGA socket)

IMG_4492.jpg


IMG_4545Medium.jpg



VGA converter board:
This took the most planning and marking up. The base hole was of the right basic size and with lots of mark-up and checking I found I could cut away plastic above and either side of the hole in the case to sink in the d-sub connector.
Rough hole:
IMG_4649Medium.jpg

Before cleanup:
IMG_4635Medium.jpg


Moodily lit:

IMG_4693Medium.jpg



I had a worry the standard VGA castle bolts would be too short to reach right through the internal cover (I was right), so now it has slightly too long Philips bolts in, but what’s in place works.

I found a header cable for one of the VGA headers to the socket, but when it arrived it was wired wrongly .. after a little research it’s now working. I just couldn’t find a ground though (it’s there surely but not marked up on the board) so I cheated and grabbed it from elsewhere.



Fit the Turbo MMC card:
The Turbo MMC card attaches to a BBC’s User Port, but the compact doesn’t have one. It does however have most of the pin outs presented at the joystick port, so I soldered the cable to the underside of the joystick port, and it works well.

With a little more dremmel-ing cutting there’s now a neat slot on the rear panel for swapping the SD card.
I double-sided taped the Turbo MMC to the rear top lip of the lower case.

Dremmel-ed slot for the TurboMMC card (and final VGA socket screws, power and audio sockets to right)

IMG_4727.jpg




Sorting out the sideways ROMS:
I checked again with thecorfiot for how the sideways rom’s work on a compact, and while I’ve not quite got the final set it now has something like 128k... the compact has as standard a 64k MOS (system) ROM, 2 x spare 16k sockets, 1 x 32k socket, and 4 sideways RAM slots as standard. The service guide says the 64k MOS rom can be swapped for a 128k with a bit of work... an update is to come in a few weeks on this, care of Mark @ retroclinic.com’s wonderful dual MOS that will add a further 4 rom slots AND a further switchable bank of 4!

Right now it has:


  • The MOS
  • ADFS
  • UTILS
  • BASIC 4
  • DFS
  • DOS FS to read PC formatted 3.5” disks (not sure if this works but I’ll give it a go)
  • TurboMMC Eprom
  • Speech! (but that’ll likely clash with the MMC card, unfortunately so presently a *UNPLUG command has sorted that out for now)
  • UPURS for playing uploading disk images over serial (transfer from a PC... just for fun)
  • 4 x 16k sideways RAM slots.
(plus ADT, beebaid, basic editor and a few others will come in a few weeks when I sort out the DualMOS)



Added RS432 serial chipset , fix the NVRAM

I knew I wanted to try out the UPURS rom to transfer disk images from a PC. But the compact didn’t have serial as standard, so I’d have to find 30 year old chipset and add it. Over on the Acorn “stairwaytohell” forums I confirmed that retroclinic.com was able to get a serial kit together, so i got one for a remarkably small sum, and its in.

Mark (retroclinic) also helpfully suggested swapping out the known-to-be- unreliable NVRAM is and for just £1 extra, removing of a resistor and a capacitor as per Mark's instructions, its done and working. Nice!

Original NVRAM (old):
IMG_4639Medium.jpg


New!
IMG_4638Medium.jpg


..and in situ: as instructed, needed a cap and resitor removing.
IMG_4640Medium.jpg



MORE holes!!:
· Added a line out out for the audio
· Added the new power 2.1mm jack
· Added a red illuminated power switch and power to the motherboard and the 8220. Maplin provided a 12v illuminated switch, the existing hole needed enlarging:
Surely this blanked off hole was here for a reason:
ScreenShot017.jpg


Lining up:
ScreenShot018.jpg


Marking up:
IMG_4637Medium.jpg


Almost done:
IMG_4651Medium.jpg


Looking good!:
IMG_4654Medium.jpg



Final lining up
Power from the 2.1mm jack simply goes to the switch and in parallel to the underside of the remaining board power jack and also to the VGA board

Lining up the final layout: bodged yellow fly lead on the right..
ScreenShot001.jpg


Testing:

IMG_4704.jpg



The kids love it!


Final pics:

Nekkid:
ScreenShot010.jpg


Clothed:
ScreenShot016.jpg


The money shots :)


ScreenShot011.jpg
ScreenShot015.jpg


IMG_4743.jpg


IMG_4744.jpg



Still to do:
1. Sort out what’s on the MCC card. Elite doesn’t work, I think there’s a fix. I read a few games don't work and there are hacks to address, so its just a matter of time..

2. I have a 3.5” floppy drive to hook up, I found a pc 5V/12V PSU on eBay, just to fix that up now..

3. Teach the kids more BASIC.. J

4. I have to get the audio output voltages right, wire up the line-out properly. The sound is presently too quiet.

5. Get the dual mos set up. Another 8 switchable ROM’s here I come

6! I now wish this was my beeb rather than the kids?


cheers, Iain


 
Looks really nice! Is there space to squidge a wee 3.5" laptop disk drive internally in there? That would be pretty awesome.
 
Simply Awesome :thumbsup:

Nice one Iain, gives me incentive to finally repair the compact I have lying around.

Nice one chap and thanks for the Beeb pr0n..

TC :D
 
Cheers!

to the cellartroll - no real room, and anyway HD's dont really feature in BBC's much. But no need - the MMC card holds all the STH archive and is only a 128mb card. Works really, reallly quickly, well integrated with the ROM it came with. Prefer cool and silent :)
 
Totally awesome green with envy mate :cool:

I tried using my Mertec Companion which adds a user port to the Compact so I could connect up the MMC Turbo PCB & SD Card. Before I did that thought I would make sure the Compact recognised the MMC Turbo ROM Chip which it didn't. Just wondering if you had any trouble on that front at all ? I was hoping it would be straight foward :(
 
Mmc rom does work on the master compact but you need to have a mmccard plugged in,

You dont need the Mertec companion as all the signals required are available on the joystick port too...

TC :)
 
I didnt have any trouble at all (beyond my rubbish soldering at the joystick port) but I also think you need the card in first.

worth double-checking which rom slot you put the eprom in and how you have those set up but think having the card in is most important

There is a bit of code somewhere you can run (ask the seller) to check if the board is functioning ok.

good luck! :)
 
BTW - an update will come soon - I thought again after the cellartroll's comment and then found a slimline dell drive will fit. Just.

I have had some troubles with the data cable, (now have an expert sorting that out for me) but as a sneak preview here's a pic.

I hope to properly update the thread in a few weeks.
 

Attachments

  • IMG_5275.JPG
    IMG_5275.JPG
    131.2 KB · Views: 20
Mmc rom does work on the master compact but you need to have a mmccard plugged in,

You dont need the Mertec companion as all the signals required are available on the joystick port too...

TC :)

Excellent thanks for the help, so if i am using MMC via the joystick port i need a lead/adaptor tailor made as i don't really want to touch the compact, any offers guys ?

---------- Post added at 00:47 ---------- Previous post was at 00:45 ----------

[/COLOR]
I didnt have any trouble at all (beyond my rubbish soldering at the joystick port) but I also think you need the card in first.

worth double-checking which rom slot you put the eprom in and how you have those set up but think having the card in is most important

There is a bit of code somewhere you can run (ask the seller) to check if the board is functioning ok.

good luck! :)

Thanks there Iain appreciated :thumbsup:
 
Last edited:
Hi if you connect the mmc to the js port you'll need to check which wire goes where and double check with a multimeter.

also check with the mmc interface's supplier, the one i got kindly provided this info:

---------------------
On the edge furthest from the MMC socket, and starting from the end with "BBC Micro MMC Interface", the connections are

CB1, CB2, PB0.... PB7

PB5, PB6 and PB7 are not used however.

The other row has two connections for +5V and the remaining eight are 0V.

---------------------

again, please check first!

in the master compact's service manual you'll find the pin outs of the js connector. see the attached image:

Myself, I just checked continuity to the underside and soldered them on there with heatshrink, lots of care are checking and more than a little good luck and poor soldering. Hence why there's no photo..

NB there's not a load of height to play with there so had to route some wires left and some right of the plug itself. Be careful putting the board back as its possible to bend it if the soldering isnt flush enough.
 

Attachments

  • ScreenShot005.jpg
    ScreenShot005.jpg
    20.9 KB · Views: 13
Finally! I got the drive cable sorted out. Which means the Internal Dell Slimline drive is in and works.

Finished pics where I cut in the slimline dell floppy drive:

The clear film stuck to the top and bottom faces of the drive is acetate. The underside of the keyboard has plenty of bare wires and it rests on the drive in places.

The cabling is convoluted for the drive and the MMC. Bit of a mess.

Dust not removed for pics :) :(


If I had more time, or started again, I'd:
a) be better at soldering to the underside of the board, it works but really its not as flash and neat as it could have been.

b) positioned the TurboMMC last of all as I put it in a silly place. a bit more to the right would be much better

c) Got the dell drive working without having to buy a cable and having it go inside>outside plug.

But it works!
 

Attachments

  • IMG_6450.jpg
    IMG_6450.jpg
    119.1 KB · Views: 26
  • IMG_6449.jpg
    IMG_6449.jpg
    101.5 KB · Views: 15
  • IMG_6447.jpg
    IMG_6447.jpg
    135.5 KB · Views: 20
  • IMG_6443.jpg
    IMG_6443.jpg
    163.1 KB · Views: 16
  • IMG_6453.JPG
    IMG_6453.JPG
    116.6 KB · Views: 17
  • IMG_6457.JPG
    IMG_6457.JPG
    78.3 KB · Views: 15
  • IMG_6455.JPG
    IMG_6455.JPG
    115.6 KB · Views: 12
  • IMG_6452.JPG
    IMG_6452.JPG
    126.8 KB · Views: 18
You can fall in love with a Master Compact when it looks like this...

Well done; great job.
 
I absolutely love this, a cracking selection of upgrades and hacks. It has inspired me to dig my Beeb out, and have a look at it again. :)
 
Back
Top Bottom