What were the differences of the various AE RamWorks cards?
(Base Board) Memory size.
There were 3 versions produced by AE back in the day, the RamWorks, RamWorks II, and RamWorks III.
The original one was additionally replaced by a RAMWORKS III basic.
Posthumously, ReactiveMicro modernized the design into a RamWorks IIII which offers up to 4MB.
Which would as well have worked with any of the original.
I'm curious what the difference was between the various revisions of the product.
All three (4) are essentially the same design.
They all provide additional auxiliary RAM banks by selection via $C073. A single 8-bit bank register would allow up to 256 banks and thus 16 MiB of RAM - that's why the RW II brochure mentioned:
Expandable to 16 Meg (3072k) with expander (piggyback) card
A claim that got carefully reworded in the RW III brochure to
Expansion Connector for possible future expansion to 16 MEG
as using a stack of 8 piggy pack boards was neither supported by hardware (no thru connector or address selection), nor desirable :))
The main difference between RW I and later is the amount of sockets for on board RAM.
RW I allowed two sets of eight 64 Ki or 256 Ki Chips, allowing a maximum of 128 or 256 KiB of Aux-RAM. That's 2 or 4 64 KiB pages.
RW II in turn squeezed double that onto the board, allowing up to 1 MiB on board.
Was it just a cost reduction?
- That's what RW III was about. It replaced several costly PAL chips by standard (MSI) TTL IC.
- RW III basic was in turn created to replace the RW I, giving the same cost reduction at the lower end (*1).
Performance improvement? Or some other feature I've missed?
Nop and nop :))
By design all of them were made to feature up to 16 MiB The 3 MiB limit was strictly due to missing of higher integration RAMs and problems with more than one sub-board. In late 1987/early 1988 AE offered a new 2 Meg+ board using standard 1 Mi chips, lowering the price. By then Apple IIe was no longer a serious contender for professional use, which maybe also explains why no 4 MiB Ramworks was designed - which the new chips would have allowed.
The reason ReactiveMicro changed it to 4 MiB is also rather cost-related to eliminating one chip while adding 33% more RAM. A low risk move as the usable bank register size is still 6-bit, so it may not interfere with any less well behaving software (*2).(*3)
*1 - The RW I / RW III basic with 64 KiB was lower priced than the original Apple 64 KiB Aux-RAM card, while offering an easy way for more: 128 KiB by plugging in another row of 64 Ki chips or 320 with 256 Ki ones.
*2 - Like some using the top two bank bits for other purpose, assuming that the card will not care.
*3 - Would be still nice to see how it behaves with 16 MiB - maybe with a switch added to disable the top bits for fringe cases. :)