Search found 366 matches

by Pr0f
Fri Aug 16, 2019 12:12 pm
Forum: Hardware
Topic: MAB 8049H P A038 comapible?
Replies: 9
Views: 267

Re: MAB 8049H P A038 comapible?

Hi, Very interesting read, but it does not say that Laurnce Reeves produced a debugged more efficient version of the 8049 called Hermes. Personally, I would use Hermes over the 8049, it works better in the QL and is still available on Sellyouretro. No - but I only meant to explain that Hermes is us...
by Pr0f
Fri Aug 16, 2019 8:48 am
Forum: Hardware
Topic: MAB 8049H P A038 comapible?
Replies: 9
Views: 267

Re: MAB 8049H P A038 comapible?

by Pr0f
Fri Aug 16, 2019 8:46 am
Forum: Hardware
Topic: MAB 8049H P A038 comapible?
Replies: 9
Views: 267

Re: MAB 8049H P A038 comapible?

With Micros's like this they offered them in various formats: EPROM piggy back - these have a socket on the back of the chip itself for the program memory EPROM Internal - device has an EPROM for Program memory on board the chip and has a clear window to allow UV erase EPROM OTP - this is the same a...
by Pr0f
Wed Aug 14, 2019 12:48 pm
Forum: Hardware
Topic: Issue 8 discussions...
Replies: 121
Views: 9616

Re: Issue 8 discussions...

Nasta put a good explanation in the ZX8301 thread, it's to do with I/O access being subjected to the same delays as RAM access when it need not be. In the Issue 6, the HAL does the decoding for the ZX8202, and it can provide DTACK.
by Pr0f
Mon Aug 12, 2019 10:03 pm
Forum: Compatibles Corner
Topic: ICL OPD (Merlin Tonto)
Replies: 10
Views: 348

Re: ICL OPD (Merlin Tonto)

For testing I am using one of those upscaler boards that handles RGB, TTL and various video formats to VGA /LCD. It has OSD that shows you the video spec coming in too - which is quite handy. Works a treat on the QL video output - I think they call them CGA / Arcade to VGA. I am not quite sure what ...
by Pr0f
Mon Aug 12, 2019 8:43 am
Forum: Compatibles Corner
Topic: ICL OPD (Merlin Tonto)
Replies: 10
Views: 348

Re: ICL OPD (Merlin Tonto)

This doesn't give you composite video, just composite sync.

You could use something like an AD724 to take the R, G and B signals and composite sync and produce composite video and or S-video. I suspect some resistor dividers may be necesary
by Pr0f
Sun Aug 11, 2019 9:05 pm
Forum: Compatibles Corner
Topic: ICL OPD
Replies: 17
Views: 1538

Re: ICL OPD

As Promised, some further updates - a picture of the board with a few sockets in place ready...

IMG_20190811_204916.jpg



also the back of the board, ready for the video mods

IMG_20190811_204746.jpg



Finally - here is an updated pdf with the latest reverse engineering...


opd decoding.pdf
(179.49 KiB) Downloaded 6 times
by Pr0f
Sun Aug 11, 2019 9:01 pm
Forum: Compatibles Corner
Topic: ICL OPD (Merlin Tonto)
Replies: 10
Views: 348

Re: ICL OPD (Merlin Tonto)

Here's a close up of the main PCB back section, where the chip swap and TP3 are:


IMG_20190811_204746.jpg
by Pr0f
Sun Aug 11, 2019 12:33 pm
Forum: Compatibles Corner
Topic: ICL OPD (Merlin Tonto)
Replies: 10
Views: 348

Re: ICL OPD (Merlin Tonto)

TP3 will be a test pad on the PCB - I can get you a close up picture when I get home tonight, showing where that needs to be connected. I plan to make that same modification too. The -5v is required for the RS422 circuit - I can't see it used anywhere else on the board, unless of course it's also pr...
by Pr0f
Sun Aug 11, 2019 8:04 am
Forum: Compatibles Corner
Topic: ICL OPD (Merlin Tonto)
Replies: 10
Views: 348

Re: ICL OPD (Merlin Tonto)

Power and video are towards the bottom of this web page - link below:

https://rwapsoftware.co.uk/oneperdesk/t ... _info.html

I will be putting up an update with some details on the keyboard and main connectors - hopefully later today, and will post more as I continue to delve into it.