Search found 19 matches

by cmorley
Tue Oct 08, 2019 12:09 pm
Forum: 8 BIT CORNER
Topic: 27C400/27C800 EPROM emulator
Replies: 34
Views: 5119

Re: 27C400/27C800 EPROM emulator

I'm loving the idea you are developing, I'm just getting back into the retro vibe with my a600 and was wondering when and how much of my money you would want. Thanks for your kind words. The prototype boards seem to be working well for people so far. The next step is to finalise the hardware layout...
by cmorley
Fri Sep 06, 2019 10:04 am
Forum: 8 BIT CORNER
Topic: 27C400/27C800 EPROM emulator
Replies: 34
Views: 5119

Re: 27C400/27C800 EPROM emulator

Working in an 8-bit machine. This is an Acorn Master using the ROM emulator/switcher to replace the 128KB MOS mega chip (contains MOS, ROMs & character set). ROM switching working from the BREAK key :) I will send this off to a friend who uses his Master daily (he did Y2K fixes and assembled MOS ima...
by cmorley
Sat Aug 31, 2019 12:37 pm
Forum: 8 BIT CORNER
Topic: 27C400/27C800 EPROM emulator
Replies: 34
Views: 5119

Re: 27C400/27C800 EPROM emulator

Would putting DiagROM and 1.3 on 512K images together with 2.04 and 3.1.4 (4 x 512K images total) work? Any preview on price and date of release for either a prototype or RC board? Yes that works. I have tried (4 of) 1.2, 1.3, 3.1, 3.1.4 & DiagROM. If you set the module up as 4x 512KB ROMs and prog...
by cmorley
Fri Aug 30, 2019 2:59 pm
Forum: 8 BIT CORNER
Topic: 27C400/27C800 EPROM emulator
Replies: 34
Views: 5119

Re: 27C400/27C800 EPROM emulator

JanHolbo wrote:
Wed Aug 28, 2019 9:43 am
Is it possible to mix rom sizes? 4 x 256K images (1.2, 1.3, DiagRom) and 2 x 512K images (2.04, 3.1.4) ?
Only with manual switches. You need A17 connected to the Amiga for 512K image but controlled by the switching for a 256KB image.

Chris
by cmorley
Sun Aug 18, 2019 3:55 pm
Forum: 8 BIT CORNER
Topic: 27C400/27C800 EPROM emulator
Replies: 34
Views: 5119

Re: 27C400/27C800 EPROM emulator

Working well in a rev 5 Amiga 500. The data buffers are HCT so 5v CMOS output levels - won't require pull ups like a 27C400 does in a rev 5... The wire goes to the _RESET signal to get ROM swithcing from the keyboard with ctrl+ A +A. (ROM switching can also be done via the USB which might be useful ...
by cmorley
Sun Aug 18, 2019 3:29 pm
Forum: 8 BIT CORNER
Topic: 27C400/27C800 EPROM emulator
Replies: 34
Views: 5119

Re: 27C400/27C800 EPROM emulator

I did a PCB to adapter to an Acorn Master MOS (1Mbit 128Kx8 mask ROM). Just sent the PCB order off.
Master MOS adapter.jpg
Master MOS adapter.jpg (133.09 KiB) Viewed 1347 times
by cmorley
Wed Aug 14, 2019 6:36 pm
Forum: PC FOR SALE & WANTED
Topic: SOLD - A500/A2000 megachip
Replies: 3
Views: 937

Re: A500/A2000 megachip

Sure you can have it. I replied to you PM.

Chris
by cmorley
Sun Aug 11, 2019 7:00 pm
Forum: 8 BIT CORNER
Topic: 27C400/27C800 EPROM emulator
Replies: 34
Views: 5119

Re: 27C400/27C800 EPROM emulator

Ha. Typical...

I'm building up the balance of the 10x PCBs I got for these prototypes and I have run out of 100nF 0402 caps! I'll put a Mouser order in tomorrow.

So looking like posting out back end of next week. I'll PM people to arrange the details with them.
by cmorley
Sun Aug 11, 2019 9:41 am
Forum: PC FOR SALE & WANTED
Topic: SOLD - A500/A2000 megachip
Replies: 3
Views: 937

SOLD - A500/A2000 megachip

Not PC but not Atari so I picked this category. I bought one of tuxbar81 on amibay's MegAChip to test compatibility with my A500 2MB RAM. Short story they clash - I'm not surprised but now I know for certain! I am not going to fit it to my A2000 motherboard so now I have an assembled and tested MegA...
by cmorley
Tue Aug 06, 2019 1:10 pm
Forum: 8 BIT CORNER
Topic: 27C400/27C800 EPROM emulator
Replies: 34
Views: 5119

Re: 27C400/27C800 EPROM emulator

Update: Firmware ported from the dev board to the prototype. Pinouts changed on the CPLD and STM32 and I altered the signal routing through the CPLD but so far so good. It's in an A500 now with 3.1.4, DiagROM, 3.1 and 1.3 programmed in & ROM switching works. Currently has the SWDIO header soldered o...

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