PDP-8/I front panel
|Design Type:||clocked random logic|
|Memory Speed:||1.5 μseconds|
|Physical Address Size:||32KW (requires optional MC8/I)|
|Virtual Address Size:||4KW|
|Memory Management:||bank selection, CPU mode|
|Bus Architecture:||negative I/O bus|
|Operating System:||TSS/8. Disk Monitor System|
The PDP-8/I was introduced in 1968 as the successor to the PDP-8. It was constructed out of TTL ICs on M-class FLIP CHIPs - mostly early standard-length single-height (width) ones, with a few dual-height. It was the first DEC computer to be built using ICs.
- KA8/IB Positive I/O Bus Interface, to allow use of newer PDP-8 devices
- DW08A Negative I/O Bus Conversion Option (on systems with a KA8/I, allows use of older PDP-8 devices)
- DW08B Positive I/O Bus Conversion Option (on systems without a KA8/I, allows use of newer PDP-8 devices)
- DW8-E OMNIBUS Interface (converts the positive bus of an 8/I)
- MC8/I Memory Extension Control, bank switching needed to support more than 4K words of memory
- MP8/I Memory Parity
- KE8/I Extended Arithmetic Element, which supported hardware integer multiplication and division, one-bit double-word shifts, and normalization
- KT8/I Time Sharing Hardware Modification, which allowed the computer to operate in either Executive Mode or User Mode
It could perform an addition to the accumulator in 3.0 μseconds, and a 12 by 12 bit multiplication with 24 bit result in 6.0 μseconds, using the math extension hardware.
The MC-8/I had three 3-bit registers: the Instruction Field and associated Instruction Buffer, and Data Field, which could be loaded either manually from the front panel, or under program control (by the Change Instruction Field - something of a misnomer, as it was actually the IB which was loaded - and Change Data Field instructions). The IB contents were loaded into the IF by a jump or subroutine call.
- PDP-8/I - Original PDP-8/I documents
|v • d • e PDP-8 Computers, Software and Peripherals|
|PDP-8s: PDP-5 • PDP-8 • LINC-8 • PDP-8/S • PDP-8/I • PDP-8/L • PDP-12 • PDP-8/E • PDP-8/F • PDP-8/M • PDP-8/A|