1 files changed, 22 insertions, 12 deletions
diff --git a/src/board_memory.zig b/src/board_memory.zig
index f99fc106..702b130d 100644
--- a/src/board_memory.zig
+++ b/src/board_memory.zig
@@ -296,11 +296,22 @@ pub fn poke(p: *Pardes, id: usize, argument: []const u8) !void {
     ) catch unreachable);
 }
 
-/// `Hexdump <addr> [len]` — len bytes, 16 to a row, hex columns and an ASCII
-/// gutter, in `hexdump -C`'s layout because that is the one everyone can
-/// already read. BYTE reads, so a partial row at the end of the space is a
-/// short row rather than a refusal, and no alignment is required: this is the
-/// word you reach for when you do not yet know what is there.
+/// Bytes per dumped row, and it is a different number on the board.
+///
+/// `hexdump -C`'s sixteen is the layout everyone can already read, and it needs 79 columns: ten for
+/// the address, forty-eight for the hex, a gap, and the eighteen-column ASCII gutter. The P4 drives
+/// a 56-column grid of which seven go to the line-number gutter, so a sixteen-byte row wraps onto a
+/// second display line and the columns stop lining up - which is the entire value of the layout.
+///
+/// Eight fits in 46 and keeps every property that matters: address on the left, fixed-width hex
+/// columns, ASCII on the right, and a gap at the halfway mark because the eye counts in fours and
+/// eights rather than in sixteens.
+const row_bytes: u32 = if (pardes.platform == .p4) 8 else 16;
+
+/// `Hexdump <addr> [len]` — len bytes, `row_bytes` to a row, hex columns and an ASCII gutter, in
+/// `hexdump -C`'s layout because that is the one everyone can already read. BYTE reads, so a partial
+/// row at the end of the space is a short row rather than a refusal, and no alignment is required:
+/// this is the word you reach for when you do not yet know what is there.
 pub fn hexdump(p: *Pardes, id: usize, argument: []const u8) !void {
     var it = std.mem.tokenizeAny(u8, argument, " \t\r\n");
     const addr = try parseAddr(it.next() orelse return Error.MissingAddress);
@@ -312,15 +323,14 @@ pub fn hexdump(p: *Pardes, id: usize, argument: []const u8) !void {
     errdefer out.deinit();
     try writeNote(&out.writer, e, requested, "bytes");
     var row: u32 = 0;
-    while (row < e.count) : (row += 16) {
-        const n = @min(@as(u32, 16), e.count - row);
-        var bytes: [16]u8 = undefined;
+    while (row < e.count) : (row += row_bytes) {
+        const n = @min(row_bytes, e.count - row);
+        var bytes: [row_bytes]u8 = undefined;
         for (0..n) |i| bytes[i] = readByte(addr + row + @as(u32, @intCast(i)));
         try out.writer.print("0x{x:0>8} ", .{addr + row});
-        for (0..16) |i| {
-            // hexdump -C's gap after the eighth column: the eye counts to
-            // eight, not to sixteen
-            if (i == 8) try out.writer.writeByte(' ');
+        for (0..row_bytes) |i| {
+            // The gap at the halfway mark: the eye counts to four or eight, not to sixteen.
+            if (i == row_bytes / 2) try out.writer.writeByte(' ');
             if (i < n)
                 try out.writer.print(" {x:0>2}", .{bytes[i]})
             else