:: Area: #0 (Private mail) Message: 30981 (Read 1 time, has 0 replies, 3303 bytes) Date : Sun Mar 21 13:50:53 2004 Subject: Sideways ROMs on the Spectrum Message 2 in thread From: Philip Kendall (pak21@cam.ac.uk) Subject: Re: Sideways ROMs on the Spectrum View this article only Newsgroups: comp.sys.sinclair Date: 2004-03-20 14:16:00 PST In article <73210e4c.0403200339.bef685f@posting.google.com>, J.G.Harston wrote: > >I've been trawling the 'net to see what other interfaces are out there >to provide extra banks of ROM at &0000-&3FFF. [ ... ] >Trawling around, I've found the following: > >ROM selection >------------- > Vehmaa Vehmaa Putnik JGH > ZXCF ZXATSP RomSwitch ROMBox Spectrum128 >Range &00-&3F &00-&3F &00-&03 &00-&F0 &00-&10 >Page ROM &10BF,n &029F,&40+n &xxA9,n &xxFD,16*n &7xFD,16*n > then &029F,n >ZX ROM &10BF,&80+x ? ? &xxFD,&10 &7xFD,&10 >RESET ROM &00 &00 &03 &00 &00 Some small generalisations: ZXCF requires ( port & 0x10fd ) == 0x10b4. ZXATASP requires ( port & 0x039f ) == 0x029f. 128K Spectrum requires ( port & 0x8002 ) == 0x0000 >Which are the most likely to be being used out there, and are there any >others commonly used. The obvious one you're missing is the +2A/+3, which uses bit 2 of port 0x1ffd to give 4 ROMs (when combined with the standard 128K paging mechanism). The Scorpion uses a very similar idea, but always pages in the same ROM when bit 2 of port 0x1ffd is set. Cheers, Phil -- Philip Kendall http://www.srcf.ucam.org/~pak21/