From 561bac75579391c14e47eaccfabdf9eda98855da Mon Sep 17 00:00:00 2001 From: Thomas Albers Date: Wed, 27 Jul 2022 18:13:20 +0200 Subject: Initial commit --- src/z80/plm.org | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) create mode 100644 src/z80/plm.org (limited to 'src/z80/plm.org') diff --git a/src/z80/plm.org b/src/z80/plm.org new file mode 100644 index 0000000..b0eef1d --- /dev/null +++ b/src/z80/plm.org @@ -0,0 +1,66 @@ +#+TITLE: PLM +#+SUBTITLE: The Pocket Lisp Machine (except its not) +#+DATE: <2021-03-03> +#+SETUPFILE: ../../options.org + +#+BEGIN_COMMENT +m4_define(`_REL_HEADER', `Next: Prototype 1Up: Z80')m4_dnl +#+END_COMMENT + +{{{date_place(Bremen, Germany)}}} + +* Background + +If you have read my article about my first [[local:/z80/prototype1.html][Z80 prototype]], then you +probably already know, what all of this is about. But, as a small +recap, the idea of my project is to build a pocket computer that can +be carried around like the pip-boy from the [[https://en.wikipedia.org/wiki/Fallout_(series)][Fallout]] series. + +The exact objectives have changed with the development of the computer +itself. I soon realized, that the way a user would interacts with a +pip-boy, was less than optimal. A keyboard was mandatory. I also +changed my mind about what processor I should use for the project, +starting with an AVR and later with a Z80. + + +As of right now, the objectives are the following: + +* Objectives + +- Have a pocket computer, that can be carried like a wrist watch + +- It should have as much RAM as its possible with a 8-bit CPU + +- It will run a lisp interpreter as its operating system + +- It would probably end up being used as a scientific calculator + +- It has to be expandable enough, so that I can be used as a pocket + Arduino replacement + +* Pocket Lisp Machine? +A lisp machine is a computer design to run lisp code. This means, it +is optimized to do so, be that through special hardware or ISA. + +Under this definition, my computer is no lisp machine. But the name +refers to the fact that it designed to run a lisp interpreter, scheme +specifically, as its operating system. + + +* Why don't I use a 6502/65816 instead of a Z80? +Between a Z80 and a 6502 I definitely prefer the Z80. Mainly because +of the instruction set and peripherals available. + +A 65816 would be easier to program than a Z80 due to the built-in +support for memory banking. But again, I still prefer the peripherals +of the Z80. + +The Z80 DMA is also a important factor for my decision. While it could +be used with other processors, I prefer to use it together with the Z80. + +The last reason is that, I began building my computer using a Z80 and +would like to complete this project using the same CPU I started with. + + +I do have the idea of building another computer in the future. This +time based on a WDC 85C816. -- cgit v1.2.3