2 Aug
2026
2 Aug
'26
9:18 a.m.
On Aug 1, 2026, at 8:42 PM, David Gesswein via cctalk
<cctalk(a)classiccmp.org> wrote:
The PDP-8 tapes are 12 bit words in low bits of 16 bit word. The other
tapes are 18 bits in low bits of 32 bit word. Both little endian. SIMH pdp-8
simulator knows about these formats.
The images only contain the data words from the tape blocks. PDP-8 tapes are
129 word per block and normally 1474 blocks. The 18 bit tapes are 256 words
per block and normally 578 blocks.
PDP-8 PIP10 will give a directory of the PDP-10 tape.
So will RT-11 FILEX, which from what ABC told me recovers the upper 2 bits in each word by
watching the CSR as the data DMA is underway, rather than doing read-all. I forgot why he
did it that way.
paul