BBC micro software by WHS
- Sideway RAM board determination program
Here's swrtype 0.7 (zip)
I made this program to find out what sort of SWR is available in a given machine. I.e. which slots are RAM, and how the RAM is selected for writing; This is one of
- none (machine without SWR)
- single (almost) always selected bank. This is what you get with 2 x 8K static RAM chips on an ATPL sidewise or Watford ROM board for example. I think the single 16K RAM banks like the 'Acorn user' SWR that fit in a ROM socket and have one flying lead to R/W are also always write-selected; depending on exactly how the chipselect works in EPROMs and the BBC it may be possible to use CHIPSELECT to select the RAM bank and thus use just one lead to get the ROMSEL method. I'm not sure, haven't really thought about it or checked the data sheets and BBC diagram.
- ROMSEL (FE30, some home made boards use this, and the Solidisk 2MEG 128K, others? Also used by the BBC B+ 128K computer). The old Solidisk boards can be made to use this method too, by not connecting to the user port (6522), but to IC76 (I've implemented this on one of my BBCs with a 3 pole switch to select between FE30 and user port). That still leaves incomplete address decoding which my program doesn't handle correctly for this method, I think)
- RAMSEL (FE32, Solidisk 2meg/4meg boards (except for the 2meg 128K), others?)
- Solidisk with incomplete address decoding (the old user port abusing boards)
- ditto with complete address decoding (don't know if it exists!)
- Watford ROM-RAM board (this is being added, not yet tested).
Are there any more SWR types?
Last modified: Thu Nov 1 23:25:10 CET 2012