New 2MB RAM upgrade for Amiga 500 & 500+

Status
Not open for further replies.
C

cmorley

New member
Rating - 100%
7   0   0
Joined
Jun 5, 2017
Posts
50
Country
UK
Region
Oxfordshire
Hello All,

I've just release my new 2MB trapdoor expansion for the Amiga 500 & Amiga 500+. It has a memory board and a Gary adapter (for extra address signals).

I own and have tested it in:
Amiga 500 Rev 3, 5 and 6A
Amiga 500+ Rev 8A

Confirmed works with:
Wicher 500i, 2MB MegAChip​

Without the Gary adapter the board will act like a Commodore A501 or A501+. i.e. 0.5MB slow in an A500 and 1MB chip on an A500+. The Gary adapter is needed to access more of the memory.

It also has a socket for a Real Time Clock (RTC) & clock battery chip for Amiga 500. RTC is Epson 72421A (or 72421B less accurate and slightly cheaper) and battery is standard CR2032 coin cell. These are still manufactured and easy to obtain if you want one.

Please note:
A500: Kickstart 1.3 or later is required for the Gary adapter (it won't boot with 1.5MB slow RAM with Kick 1.2)
A500: A 1MB/ECS Agnus is needed to do the chip RAM mod (to get 1MB chip RAM & 1.5MB slow RAM)
A500+: Unless you do the chip RAM mod then you don't need/fit the Gary adapter
A500/A500+: For maximum memory you need to solder some jumper wires. Only attempt modification if you have the right tools and are confident in working on your Amiga.

Full details are on the website including installation instructions and chip RAM mod details.
http://www.boobip.com/hardware/A500_2MB

Please ask if you have any questions or an unusual setup.

Memory board, Gary adapter & link wire:
2MB-board set.jpg

More photos on the website including pictures of it installed in A500 and A500+.

2MB memory PCB - £25
Gary Adapter and cable - £5
+ P&P from £2 UK, £4.15 EU, £4.80-£4.95 World

Current stock is blue PCBs.

Available elsewhere.

Chris
 
Last edited:
2wk bump. Still some green boards left. New batch of blue 10+ available.
 
Pending questions regarding already existing 1MB Chip-RAM mod.

EDIT: Got my question answered by simply writing them down and thus thinking about them in detail.
 
Last edited:
Bump. Still in stock. Only 2 green kits left though, plenty of blue.​
 
I didn't buy mine here, but, can confirm it works nicely in my Rev6A with Wicher500i and 2MB megachip expansion. Chris was great with support in getting it to work with the Megachip + the Gary Adapter.
 
Expressing interest in one full set (Expansion plus Gary adapter). If available, green but blue would be okay too.

PM Sent
 
Hi.
I bought this from eBay last week. I have not received it yet, but couple of questions for future. I found old RM-550C from trapdoor of my a500. My plan is recycle ram and rtc chips. So can i use old RTC (OKI M6242B) in your board?
-Jarkki
 
zJark said:
Hi.
So can i use old RTC (OKI M6242B) in your board?
-Jarkki
Click to expand...

No, you need to use RTC72421A or RTC72421B which have an internal clock crystal. M6242B needs an external crystal and other components on the board as well. They are not compatible ICs.

RTC72421A is a little more accurate than RTC72421B.
 
Last edited:
cmorley said:
zJark said:
Hi.
So can i use old RTC (OKI M6242B) in your board?
-Jarkki
Click to expand...

No, you need to use RTC72421A or RTC72421B which have an internal clock crystal. M6242B needs an external crystal and other components on the board as well. They are not compatible ICs.

RTC72421A is a little more accurate than RTC72421B.
Click to expand...

Oh Ok. Thanks. Allmost forgot that another question. I have that stripped a500+ board in my a500. If i want that full 2meg i need to install missing ram chips and that logic chip in MB. I install sockets so it is easy change chips if something goes kaboom.
Ram chips in MB are hyb514256b-70 .... Now in that old trapdoor expansion i have hy51c4256s-10 chips. can i use them in my mb.
Quick googling tells me that difference is access time 70ns vs 100ns . Is that a problem?
-Jarkki
 
Status
Not open for further replies.
Back
Top Bottom