Sinclair QL Floppy Disk Interfaces

[vanpeebles]

I have that too, but isn't it a pain? Characters are hardly legible in 512x256, and single pixels (e.g. at the border) can not be distinguished. Do you use it in 256x256 only?

I did a thread about mine here: http://qlforum.co.uk/viewtopic.php?f=2&t=12

I use monitor mode all the time and it works fine It could be a difference in your wiring or maybe because it's a german QL possibly? Or maybe the GBS board as there are a number of versions.

[1024MAK]

Mark, what do you mean? Why SRAM? Or, what do you mean, "modern" DRAM? As in... DDR perhaps?

I mean use one (or maybe two) 512k x 8 bit SRAM chips instead of the DRAM chips used on a Gold card (for example) so that the QL has more than it's standard 128k RAM.
I'm not sure where the price cross-over is these days with DRAM modules. If someone was going to recreate a Gold or Super Gold card, DRAM may be needed, as larger amounts of SRAM may not be suitable.

Mark

[skagon]

Again, I don't understand why SRAM? The original QL design does not use SRAM and neither do the Gold or SuperGolds. Technically speaking, the maximum you could have on a QL without reverting to hackery is, if memory serves, 768k, as the 68008 package that's used in the QL only has 20 address lines : 2^20 = 1048576 = 1MB addressable memory.
The Gold and SuperGold make this limitation irrelevant, as they've got a different processor on-board, and separate RAM and ROM on-board, so they're using the QL RAM only as a double-buffer for the graphics. Essentially, everything runs on the Gold/SuperGold and the rest of the QL board is used for I/O.

So, if you want a RAM expansion for the QL (without using new processors), a plain 512k DRAM module should be more than enough.

[Dave]

SRAM is so much easier to work with than DRAM. It requires no refresh, runs at a much greater range of speeds, is far more tolerant - it really helps simplify designs if you do not have a huge budget.

[Peter]

Normally, SRAM helps simplify designs if you do have a huge budget. It is far more expensive - just the small size needed for traditional QL purposes makes the price irrelevant.

[1024MAK]

One SRAM 512k x 8 for £2.79+VAT, not going to break the bank

Mark

[skagon]

If we're talking about designing a RAM expansion module for the original QL board, there are ready-made designs that work like a charm and only use basic 74LS for glue logic. No need to reinvent the wheel, is there?
If we're going into designing something else, though... that's a whole new ball game.

[Dave]

An SRAM expansion is faster than a DRAM expansion.

Still, at the end of the day, it is up to the designer to design the board and specify the components.

What's for sale again?