Search found 369 matches

by Pr0f
Fri Sep 13, 2019 10:56 pm
Forum: Hardware
Topic: 2 ql's and roms ?
Replies: 4
Views: 169

Re: 2 ql's and roms ?

Early versions of the QL had a 3rd ROM in the ROM port and the 2 internal ROM sockets filled - these were 16K ROM's or EPROMS as the original intention was to get the OS and BASIC into 32K, but the ROM grew to 48K. The ROM dongle was moved internally, hence the piggy backed ROM's and flying lead - e...
by Pr0f
Fri Sep 13, 2019 6:23 pm
Forum: Hardware
Topic: 2 ql's and roms ?
Replies: 4
Views: 169

Re: 2 ql's and roms ?

You can also solder 2 ROM's on top of each other if they are a set, as both sockets are in fact wired the same way, but the jumpers need to be wired for the 2 ROM setup - the advantage of doing this is it keeps one ROM socket free, for QL-SD or similar interfaces.
by Pr0f
Wed Aug 21, 2019 11:22 am
Forum: Hardware
Topic: Issue 8 discussions...
Replies: 125
Views: 12072

Re: Issue 8 discussions...

Did someone not have a 'recreated PCB' for the issue 5 or issue 6 board as a bare pcb - i am sure I haven't dreamt that... I could use one as I have a QL that's got some damaged tracks under the memory, and as a fix I am contemplating a piggy back board lifting the ZX8301 onto the board with a singl...
by Pr0f
Fri Aug 16, 2019 12:12 pm
Forum: Hardware
Topic: MAB 8049H P A038 comapible?
Replies: 10
Views: 744

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: 10
Views: 744

Re: MAB 8049H P A038 comapible?

by Pr0f
Fri Aug 16, 2019 8:46 am
Forum: Hardware
Topic: MAB 8049H P A038 comapible?
Replies: 10
Views: 744

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: 125
Views: 12072

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: 1065

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: 1065

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: 1842

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
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