Issue 8 discussions...
Posted: Wed Mar 20, 2019 11:49 pm
Sooo, to kick things off, would people be terribly offended if all the 7400 series logic was SMD instead of DIP?
RIP Sir Clive Sinclair 1940 - 2021
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Me too!Peter wrote: But I'm interested in high functional and mechanical equivalence to the QL.
All the SMD components would be mounted for you. Mostly, it's DIPs changing to SOICs. The reliability would be there, so socketing for easy changes is unneeded. It also gives a bit more flexibility in the design - though it is nice using DIP components because the pins penetrate all four layers. They always hit +5V and GND without tracks and vias. The passives are never smaller than US 0805. The smallest component on the board is a TSSOP5 single inverter gate.NormanDunbar wrote: I suppose that question depends on who is having to do the soldering ("soddering" for the USA
I've done some hand soldering of SMD stuff, and it's a tad finiky, but no tombstones. (Yet!)
It IS a temptation. Feature creep is the enemy. The catch is there are essential changes, and the work to do those is 90% of the work for the new feature. IT'S A TRAP! Currently, the main work seems to be focused on eliminating the 8301's stranglehold on the system. It occupies the bus far too much of the time. Its generation of DTACKL is also problematic. Since it wouldn't play nice, we're taking all its toys away.Peter wrote:Especially if only larger, easy to solder SMD footprints like SO are meant, that's absolutely fine for me. But I'm interested in high functional and mechanical equivalence to the QL.
For my taste, it should be able to run 128K RAM if configured, support microdrives, and unchanged operating systems. I also like the idea of re-seating most socketed QL chips to this board.
For me, the Issue 8 board should cover those traditional QL features, looks and add-ons the Q68 can not offer.
If I designed the board myself, I'd be in temptations to improve and change a lot of things. But I think most of those temptations should be resisted. Make it a true QL, very last Issue!
The explicit mention of these two bewilders me a little. I hope the board remains so close to the QL, that unchanged QDOS works also. (And I think you mentioned that earlier.)Dave wrote:Currently, it looks like the machine will have Minerva at launch and SMSQ/E shortly thereafter.
We probably talked about a Q68 style bootloader that pulls a ROM image from SD card and then triggers a hardware reset. Porting the Q68 loader to a QL with shadow RAM should be possible, but I see danger of breaking the principles that I hoped to find in this mainboard. E.g. I hoped for existing original ROM sockets and the boot process unchanged (at least as an option).Dave wrote:I've been quite intrigued by an idea you explained in a post a couple of years ago, which would greatly simplify booting and occupying shadow RAM in the ROM areas.
If it can not run at original speed and with unchanged QDOS, the board would lose it's special "retro" charme for me. Which is of course a matter of taste.Dave wrote:It does support microdrives and QLNET under Minerva. If the system is supplied with a slightly faster clock, we will modify Minerva so timings are correct.
Video is a problem also for myself - so I understand this is tempting. On the other hand, if the mainboard goes forDave wrote:The main area of discussion right now is the video subsystem. It's a possibility we might move the whole thing including 8301, internal video RAM, 245 and 257s to a daughter card, so the entire video system could be upgraded later.
Again I hear "speed change"Dave wrote:I do have a number of 32K dual port SRAMs, which would completely free the CPU from video timing constraints. This could more than double the speed of the QL and remove a lot of timing restrictions.
Don't worry, the default configuration is exactly an old QL except for one difference (which could also be disabled), of having 1M of SRAM on board - and it can use the original ROMs. The main difference in ROM sockets is that they will be quality turned pin onesPeter wrote:The explicit mention of these two bewilders me a little. I hope the board remains so close to the QL, that unchanged QDOS works also. (And I think you mentioned that earlier.)Dave wrote: Currently, it looks like the machine will have Minerva at launch and SMSQ/E shortly thereafter.
Fantastic! My taste for this mainboard is very high quality, even if I have to pay more.Nasta wrote:The main difference in ROM sockets is that they will be quality turned pin ones
That's good - although I'm not sure what will happen to some favorite games. If speed increases too much for normal gameplay, some way of slowing down would be important.Nasta wrote:The timing is changed in the sense that everything can work ~zero wait but the default clock is still 7.5MHz exactly the same so MDV, NET all work excatly as before.
Opinion: The Q68 supports screen 1. A QL mainboard should not fall behind the Q68 in compatibility.Nasta wrote:The one thing we are debating at the moment is screen 1 support, so opinions on this are welcome.