On 2023-01-23 6:04 p.m., Chuck Guzis via cctalk wrote:
Now, I'm getting 64GB microSD cards for just under $5 each.
--Chuck
I just want the cheap $1 16 meg SD cards. To quote Dr Who. "The original
you might say." I have project uses small magnetic media, like a RK05.
More I look at DEC's PDP 11 I see it less friendly than
the PDP/8. The PDP 8, was one simple box you could get cheap used. The
11 is mess of mix and match components that always had a big commercial
price tag. The only thing that was personal was the Heath Kit 11, and
that had no mmu and only 8" floppies.
Expanded memory with a MMU was really pushed for computers with a 16 bit
address space. PDP 11,6809,8086,Z8000 in the late 70's, early 80's.
Hindsight has proven you need a real non segmented address space of 20+
bits, like 68000,386.
I have FPGA design, that has 19 bit address space with no mmu, as simple
32 bit cpu with 8 registers plus a PC. The base machine uses ~ 48 kb for
user programs and ~32Kb for a very basic O/S using a simple FAT for two
drives like a RK05. Memory requirements place a TTL version around 1976
using mostek 4096 drams.A 2901 version around 1978, with 16K drams.
(The FPGA emulation).A 3 half word floating point format is planned.
This is to compete with the PDP 11/PDP 10 using 8 bit bytes.
I have nice design using 10 bit bytes to compete with the PDP/10
with a similar opcode layout.
Ben.
