IBM 3540 diskette is still mentioned in JCL reference, which caught my attention.
I have reviewed some materials but still have many questions: 1. Was it popular equipment or it was rather rarely used? A1: IBM 33FD drive was used inside M/T 3540 and was popular as card reader/punch (M/T 2501 M/T 2540 and M/T 3505/3525) was not ecologically correct (punch cards) and are slow to process data and become obsolete and/or out of service from IBM. 2. What was the purpose of 3540? Was it (early) replacement for punched cards? A2: At that time, I see no other purpose for it. It was smaller, quiet, and faster if compared with M/T 2501 M/T2540 and M/T 3505/3525. 3. What was the capacity of the diskette, roughly? A3: It was designed to R/W 8-inch diskettes with about 256KB capacity. Later was introduced 8-inch dual density diskette which increased capacity to 1.0MB. 4. Files naming and organization (subdirectories). A4: Basically, it works as CKD devices works, with, track0, sectors, blocks, cylinders, CRC, etc... 5. Was it used as R/W device (that means it could read from diskette and write to it)? A5: Yes, M/T 3540 can read, it was a more used function replacing card reader machines but can write diskette too to substitute punch card machines. 6. AFAIK there was autoloader there. How were the diskettes changed? Was it mount request as for tapes? A6: Yes, there was an autoloader, very similar used in M/T 3747 (Diskette Converter Unit). It works like card readers, so if you load diskette and press start button, it will generate an interrupt to Operating System and start to read data. To write diskette there was a Operating System asking to load an unprotected diskette. To keep things easy, normally M/T 3540 were defined with 00C (reader function) and 00D (punch function). 7. How was it connected to the host? Bus & Tag? A7: Yes, M/T 3540 was connected to /370 systems and subsequent using blue cables Bus & Tag. Never have an Escon connection, unless using an IBM 3094 Converter Unit. 8. Was it defined in IODF as a CU and DEV? A8: Yes, it was defined like any other device in Operating System, but have only one CU and only one Dev. I do not remember if CU was same to reader DEV and punch DEV or need to define one CU for each. Good old times in computer operations room!!!!! -- Carlos Bodra IBM zEnterprise Certified São Paulo – SP – Brazil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
