Early Multibus Intel floppy controller boards Herb Johnson last update Aug 23 2018 thanks to Roger Arrick, Bill Beech, others ======================== Guide to Intellec Microcomputer Development Systems (McCracken) Intel, 1978 9800558B https://archive.org/details/bitsavers_intelMDS9878_3359978 -------------------------- SBC 201 - SBC 211 SBC 212 floppy controller set Diskette Hardware System, Hardware Reference Manual http://www.nj7p.info/Manuals/PDFs/Intel/9800349B.pdf SBC 211 or SBC 212 Diskette Hardware System contains SBC 201 "intelligent controller" two board set: implementing an FM (single density) format SBC 201 set consists of "Channel board" and "Interface Board" Channel Board with INtel 3000 series microcontroller chipset - boards labled "Floppy Disk Controller Channel" ?? 1000467 - PWA (board) number 1000468 - Controller Channel artwork 1000469 - C. C. schematic number microcode for FM - part or revision number? Interface Board to drive, decodes/encodes disk format - boards labled "Floppy Disk Interface (XXX)" by drive XXX = CDC, etc. 2000603 - PWA (board) number 2000604 - interface artwork number 2000605 - interface scheamtic ---------------- "SBC 202 Double Density Diskette Controller HRM" http://www.nj7p.info/Manuals/PDFs/Intel/9800420A.pdf SBC202 floppy controller set (Roger Arrick) http://www.rogerarrick.com/mds888/ SBC 202 set consists of "Channel board" and "Interface Board". Channel Board with INtel 3000 series microcontroller chipset - boards labled ?? 2000469 - C. B. schematic number 1000467 - PWA (board) number and artwork? - 1000467-05M from M2FM board-set Microcode for M2FM - part or revision numbers? - 9100277 on one PROM for M2FM Interface Board to drive, decodes/encodes disk format - board labled "Floppy Disk Interface - Dual Density" 1001037 - Interface artwork 2001531 - Interface schematic 1001036 - Double density interface PWA jumpered and parted for M2FM? About SBC 201 vs 202 and MFM vs M2FM DD operation. "[The disk interface board] can be jumpered for MFM, but it's not standard MFM. [The channel board would] still use the Intel header and sector format, including address marks, which are not at all like IBM format. The only thing that is interchangeable is the 201 and 202 Channel Boards, if you swap the PROMs. The single and double density interface boards are totally different." - Eric Smith Bill Beech adds "[MFM] is why Intel developed the 8271 and 8272 [instead of developing a new MFM ROM set for the 202]. " Example SBC 202 board set (Roger Arrick MDS-800/888) http://www.rogerarrick.com/mds888/ PWA 1000467-05M "Floppy Disk Controller Channel" board M2FM - one ROM has 9100277 PWA 1001036-01A "Floppy Disk Interface - Double Density" board M2FM Example board set (Bill Beech via eBay) PWA 1000467-005 rev T JG, "Floppy disk controller channel" S/N 024875 - channel board with microcode ROMS -- 1010468-001, 102877-001, 101472-001 101471-001 PWA 123857-002 rev C "Floppy disk interface double density" S/N 020481 --------------- SBC 201/202 ROMs, Eric Smith All SBC 201 and 202 PROMs are Intel D3604A or equivalent 512x8 open collector 70ns 24-pin DIP (600 mil width). Three-state PROMs (e.g. Intel D3624A) will probably work fine also. Other vendor's pin-compatible PROMs should be fine as long as they are 70ns or faster, e.g., Open collector: AMD Am27S30 Fairchild 93438 Harris HM7640 Intersil 5605 MMI 6340 National 87S295 National 74S475 Signetics 82S140 TI 74S475 Three-state: AMD Am27S31 Fairchild 93448 Harris HM7641 Intersil 5625 MMI 6341 National 87S296 National 74S474 Raytheon 29625 Signetics 82S141 TI 74S474 TI 28S46 The four-digit 02xx number is the specific D3604A pattern number, which is the less important of the identifying numbers, as it is only unique to the D3604A, and the same number might be assigned for entirely different contents on different Intel base PROM part numbers. The 52-xxx or 91xxxxx numbers are the actual development system replacement part ordering numbers, and should be unique. It is almost certain that there were earlier version of some of these, especially A13 for the SBC 201 and A11 through A13 for the SBC 202. Based on the limited amount of Intel service documentation available, I think the versions represented here are the final released versions. SBC 201 A10: 0236, 52-606 leftmost, near edge of board SBC 201 A11: 0237, 52-607 SBC 201 A12: 0238, 52-608 SBC 201 A13: 0239, 52-633 rightmost, near D3001 SBC 202 A10: 0230, 52-722 leftmost, near edge of board SBC 202 A11: 0261, 9100277 SBC 202 A12: 0233, 52-741 SBC 202 A13: 0232, 52-735 rightmost, near D3001 ------------------ "iSBC 204 Flexible Diskette Controller HRM" http://www.nj7p.info/Manuals/PDFs/Intel/9800568B.pdf single Multibus board with 8271 FDC and 8257 DMA chips and hardware data seperator 8" floppy drive connector supports FM single density IBM and non-IBM formats - board labled "??" - PWA board number 2003209 - Schematic number 1001584 - assembly drawing number -------------------- "iSBC 208 Flexible Disk Drive Controller HRM" http://www.nj7p.info/Manuals/PDFs/Intel/143078-001.pdf single Multibus board with 8272 FDC and 8237A DMA chips iSBX Multimodule connector edge connectors for 5.25" and 8" floppy drives supports FM single density or MFM double density, IBM and non-IBM formats Eric Smith noted in Aug 2018, "As far as I can tell, Intel didn't "develop" the 8272; they just licensed the design of the NEC uPD765." - board labled "208 Flexible Disk Controller" 143275 - PWA board part number? 143275 - board layout drawing number 143556 - schematic number ---------------------- Alternatives are these (Roger Arrick, Eric Smith): Zendex ZX-200A Floppy Controller replaces SBC-201 AND SBC-202 Zendex ZX-203 Floppy Controller replaces SBC-201, 202, 206. - has Signetics 8X330 FDC chip, supports Intel M2FM Zendex 203 firmware, disassembly: - https://github.com/brouhaha/zx203-fw National Semiconductor BLC-8201, replaces Intel SBC-201