Burroughs L-series

--------------Original Message------------- -------------Reply------------- Ah, another ex-BBM/Unisys type; hi! Frank McConnell very kindly directed me to: news:comp.sys.unisys Don't know how many people on there are collectors, but they're certainly interested in Burroughs & Unisys stuff. What are L's? Glad you asked: The L series was a type of computer that's largely ignored by the historical community, often written off as _just_ an accounting machine. First there was the F series which, along with Monroe and NCR equivalents, could be found in pretty well every small bank back in the 50s & 60s. Completely electro-mechanical, they were basically multi-total adding machines with a wide carriage for ledger cards and journal paper rolls. If you think a Selectric is a complicated system of levers & springs, you've never seen the insides of one of these babies; they were "programmed" with different length metal pins inserted in specific locations in a program panel running the width of the machine. Printing was done with type bars for the numeric data and a type box for alpha (if an alpha model). They were superseded by the E series, which replaced the levers and springs with discrete transistor logic and core memory (and an interesting device called a "magnetic core counter"). They also added the capability to read data off a magnetic stripe on the back of the ledger cards which stored constant data (client name etc.) and running totals, and PPT I/O. The replacement L series started out (L 2000 to L5000) with mechanical keyboards and a Selectric ball printer, a small fixed hard disk for RAM, and IC logic. The L6000 replaced the keyboard with an electronic version, the L8000 replaced the memory with IC's (2102?), and the L9000 replaced the Selectric ball with a dot matrix printhead. They were programmed in assembler, Cobol or a Report Generator (usually cross-compiled on a larger system, although there was an on-board assembler available). They all had an integrated PPT reader (mechanical or electronic) for loading firmware, and also programs if there was no cassette or mag stripe reader. The IC RAM models also had a battery-powered DC300 tape drive for saving & restoring memory in case of a power failure. Optional peripherals included PPT I/O (Tape and cards), up to four digital cassette drives, a separate batch mag stripe reader and datacomm (TC series). One interesting feature was the two independent form tractors on the printer, essentially giving you two (three, if you count the ledger cards) separate printers, side by side, with only one printhead. Not all models used ledger cards and, especially with four tape drives, they made a pretty good all-purpose computer; one of my installations generated BOMs for an aluminum window manufacturer, for example. The last models of this type (AFAIK) were the B80 & B90, which added 8" floppy disks, 14" 5MB hard disk cartridges and a video display (either a Panaplex or a CRT). Aside from the one thing all these models had in common, the integrated keyboard and wide carriage console, they had essentially become "normal" mainstream micros and were superseded by B20s etc. mike