22 Jun
2025
22 Jun
'25
8:15 p.m.
On Mon, Jun 23, 2025 at 3:59 AM Frank Leonhardt via cctalk
<cctalk(a)classiccmp.org> wrote:
These were not normal audio cassette recorders. They were units with
several motors and solenoids so that the tape motion was controlled by
the electronics. The 'ASR unit' -- the unit bolted on top of the
normal Silent 700 -- contained buffer RAM, I think the data on the
tape was stored in blocks so when doing key-to-tape, your keystrokes
were stored in the buffer, then when the buffer was full, a block of
data was written to tape.
There were several such models. The older one was the ASR733 which was
all TTL. The ASR742 had a 8008 in the main part of the terminal but I
think the tape unit was still all TTL.
FWIW I am sure I've seen single tape drives with a pair of RS232
sockets on the back to link between a terminal and modem and give
'ASR' facilities -- recording data to tape in blocks and replaying it
later.
-tony
There was a
version of the Silent 700 terminal which had a unit on top
containing 2 digital cassette drives [1]. These 'replaced' the paper
tape punch and reader of other ASR terminals, I think you could save
data from either the line or keyboard onto a caseette (equivelent of
punching paper tape), copy from one to the other editing as you go and
send the data from cassette to the line or printer (equvalent of
reading a paper tape).
[1] Same dimensions as a normal audio Compact Cassette but with a
different grade of tape (higher coercivity?). You can identify the
cassettes by the slightly off-centre notch in the rear edge.
I never saw one of those, but that's the sort of thing I was as talking
about. The BIOS on a lot of the 8-bit micro boards I used was agnostic
as to whether it was a cassette tape interface or serial reader/punch.
The only snag was that the cassette couldn't start and stop on a
per-character basis so you couldn't realistically make a tape by keying
as you could with paper, and you had to insert nulls on the end of a CR
to allow time for processing a line that had just been input. Microsoft
BASIC had a NULL command to set the number of nulls required. So how, if
it could, did this Silent 700 make a keyed tape?