Mar 7, 2018 · The PDP-8/S, which arrived shortly after the original PDP-8, was in this category; however, because it used a serial arithmetic unit, it was slow and of limited popularity. The PDP-8/L, a computer using the same technology as the PDP-8/I, but with fewer available options, also had its logic behind the front panel.

May 31, 2014 · PDP-8 programs that emit predefined messages almost always use the upper-case only 64 char TTY set, and store them as two 6-bit chars per word. The DEC PDP-8 assembler (PAL) (except the earliest editions) includes directives to pack literal strings.

Mar 2, 2018 · The PDP-8 designers wanted memory reference instructions (MRI) like TAD to be able to address zero-page, indirect, current-page, and zero-page-indirect memory references, which requires 2 bits in the instruction word: 00, 10, 01, and 11, respectively. That leaves 7 bits for MRI instructions, which gives the PDP-8 page size of 2⁷ = 128 words.

Jan 12, 2024 · This answer is written from information sourced from PDP-8/E & PDP-8/M & PDP-8/F Maintenance Volume 1 (PDF warning). Here is a description of the datapath allowing the program counter to be incremented on the PDP-8/E, this is figure 3-2 in the book):

Feb 2, 2025 · All the PDP-8 I know have magnetic core, and you can see in the OS/8 manual that the manual authors also made the assumption "it's magnetic core, and keeps the value". If you have any information about existing installations with semiconductor memory, then the next question would be what other periphery they were using, and if they were using ...

Oct 20, 2016 · The static load is an irreducable 5 instructions per additional word of precision. The dynamic load is 8 to 11 cycles per word of precision, depending on indirection. The PDP-8 programmers I worked with at DEC felt this arrangement of operations was the most easily proved correct. Some DECUS contributors may have had other opinions.

Jan 10, 2024 · I'm trying to find a single clear statement of the limits to the numbers represented in the PDP-8's three-word format. I found the original documents on this, but they are, ahem, not exactly forthright with this information. Page 3.10 shows the format with the exponent in the first word and the mantissa in the next two, but the exact format of ...

Feb 4, 2024 · Furthermore, the PDP-8 and PDP-11 are very different architectures, and their assembler is quite different. An example of a machine which is similar to the PDP-8 is the HP-2100, even though it is 16 bits, the instructions are much more similar and the architecture is more similar to the PDP-8.

Jan 12, 2024 · The PDP-8 was a remarkable exercise in minimalist computer design; some of the aspects of its design are discussed in detail at PDP-8 transistor count One feature it did not have was a stack. Instead, ...

Jul 25, 2019 · The PDP-5's instruction set was later expanded in its successor, the PDP-8, to handle more bit rotations and to increase the maximum memory size from 4K words to 32K words. The part about the increase in max memory size I believe is false, since that's done by optional external hardware, the Memory Extension Controller which presumably may ...