Hardware incompatibilities

[RWAP]

I was surprised today when trying to sort out a working disk system for a QL customer, by some of the apparent incompatibilities between QL hardware.

Technology Research Limited disk interface (this has a built in parallel port as well as a disk interface - I did not get around to seeing if it had memory or not).

This was tested with toolkit II EPROMs with the following (surprising) results:

- 2 x Toolkit II EPROMs were not identified and could not be used.
- 1 x Toolkit II EPROM was recognised, but then the TRL disk interface was not linked in.

Very odd - I guess the reason between the three results was more down to the link code in the TK2 eprom - this might have changed over the different versions, so that instead of the Toolkit II EPROM being installed last, it was installed first.

It did not work with a 512K expanderam, so presumably has some memory built in.

PCML Q+Disk Interface
I have 3 of these - one of which does not work with disks (needs a new WD1770 controller probably), so I did not try it.

The other two interfaces appear to have 256K and 128K built in respectively.
Both work with Toolkit II.

However, when plugged into 256K Expanderam, the QL goes through the memory check pattern and then displays a white screen suggesting a RAM issue (maybe a timing issue?)

[vanpeebles]

I had a white screen while testing the 512k expanderam on an older QL.

[belg4rion67]

Hi, is a strange thing because I've installed on my original QL with Minerva Rom ver 1.98 a 512 K expansion ram buyed to Rich' site and works perfectly...
Is my opinion that some chips on expansion board have timing problems

[RWAP]

Hi, is a strange thing because I've installed on my original QL with Minerva Rom ver 1.98 a 512 K expansion ram buyed to Rich' site and works perfectly...
Is my opinion that some chips on expansion board have timing problems

Is that the expanderam or the Q+disk interface?

[belg4rion67]

Hi Rich, sorry for delay: is a simple ram expansion unfortunatly without pass connector, in fact I'm looking for disk if with on-board ram
On my expansion there are all LS chips then I suppose that they are fast enough to follow the QL clock

[RWAP]

You may spot that I have listed a Gold Card on sellmyretro.com

I may have another PCML Q+Disk Interface here which supports DD disks, has some onboard RAM and a cut down Toolkit II

I will test it when I get some time, and see if I can get it to work - I had put it in my spares box, but then I found one of the pins on the QL's expansion connector was loose, so that may be why it did not work!

I also have a TR Beta-Disk interface with built in memory and parallel port - which is something that started this thread - not sure it is worth while selling, as it does not seem to work with Toolkit II !!

[belg4rion67]

Hi Rich, as in www.sellmyretro.com there are two kind of replace board for QL (an issue 7 and issue 5.2) do you know if there's some great difference between them? Differences between external connectors are known but another ones? That is because I will connect a Sandy super Qboard to one of them.

Many thanks and best regards
Paolo

[RWAP]

There is no great difference between the issue 7 motherboard and the US v5.2 motherboard, so far as I can tell (the US motherboard is set up for extra shielding) but looks to be based on the Issue 7 motherboard.

The issue 6 and (UK) issue 5 motherboards look quite a bit different.

[belg4rion67]

Many thanks Rich for your kindly response: I'll order immediatly the new motherboard
See you soon !
Paolo

[nichtsnutz]

Hello all,

if the v5.2 motherboard is a USA version then it could be that it has an ZX8301 ULA with different timing because of the NTSC TV standard in the USA.Maybe this will not work on a PAL TV !
It would be interesting to compare the type of the ULAs.

Greetings,
Vassilis