Starting Skate
I’m building Skate, a Scheme compiler for Z80/CP/M. I’ll release the implementation in stages and explore how to make its expressive style of programming practical on a small machine.
Series: buildingskate - 2026
A minimum viable Scheme
I’m building Skate, a Scheme compiler for the Z80 running CP/M. Examples from Structure and Interpretation of Computer Programs provide a test of how much we can retain while leaving enough memory to run useful programs.
Scheme within limits
Skate’s design balances useful Scheme features against the memory and processing limits of Z80/CP/M. Some features remain central; others sit outside the scope of the first version.
Room to run
Skate brings compiled Scheme to Z80/CP/M. Providing automatic memory management on a small machine means balancing runtime size, data capacity and processing time.
Taking out the garbage
Skate reclaims list pairs that a running program can no longer reach. Its collector traces from live roots, keeps reachable pairs and returns the rest to the free list.
Building a heap out of slabs
Skate divides its small heap into 256-byte pages. Pairs, bindings, closures, strings and vectors can then share the available memory without fixed reservations for each type.
Making space for closures
Skate implements lexical closures using heap binding records and pointers. Following a small adder example shows how those bindings survive a procedure call on a Z80.
Years
- 2026 (7)